1. Field of Invention
The present invention relates to power line self-latching clamps for grounding and other purposes.
2. Description of the Prior Art
Commonly owned U.S. Pat. No. 4,846,725, of which applicant is an inventor, relates to a self-latching power line clamp. Clamps having structure of the type described in this patent have been generally successful in solving problems in earlier situations when it has been necessary to connect protective grounding equipment to electrical power distribution lines. The grounding equipment was mounted at an end of an elongate insulative rod, known in the industry as a "hot stick," and raised for connection onto the power line.
As an example of problems encountered prior to U.S. Pat. No. 4,846,725, typically the earlier types of grounding equipment had a stirrup or notch which was placed over the power line. The earlier grounding equipment also included a rotatable threaded rod or bolt having an eyelet at a lower end and a gripping jaw at an upper end. The bolt and eyelet were rigidly held in a hollow upper portion of the hot stick as the grounding equipment was raised to the power line and the stirrup placed on the power line. The bolt and eyelet were then released from the hot stick so that a hook at an upper end of the hot stick could engage the eyelet.
Engagement by the hook-mounted hot stick was by nature a relatively loose one. The hot stick could then be rotated by the line crew, moving the bolt inwardly, as long as the hook engagement with the eyelet was maintained. Rotation was continued until the gripping jaw firmly held the power line in place in the stirrup.
So long as the power line was in a substantially horizontal plane and the line crew on the ground below, these earlier apparatus with rotatable threaded rods were generally adequate. There were several situations, however, where problems were present.
For example, there were a number of types of electrical power distribution equipment from which the power lines extended in directions other than horizontally. Breakers and transformers where it was not unusual to have the power line at angles of 45.degree. or more from the horizontal were examples. With power lines in non-horizontal planes, the earlier types of grounding equipment tended to slide down the power line or fall off the line. It was also a difficult task to rotate the threaded rod which was only loosely engaged at its eyelet with the hook on the hot stick.
Another problem situation occurred when the line crew member was working to attach a clamp, even on a generally horizontal line at about the same elevation. Again, manipulation and rotation of the threaded rod was a cumbersome and awkward task.
Apparatus according to commonly owned U.S. Pat. No. 4,846,725 have in a large measure overcome these problems. There have been situations, however, when the release mechanism for the gripping jaw of the type in U.S. Pat. No. 4,846,725 could be triggered by incidental contact with some object or thing before the power line was in position in the gripping jaw of the clamp. When this occurred, the clamp had to be re-armed or re-loaded. This was an inconvenient and at times cumbersome operation. Further, the contact spring of the trigger mechanism was in a relatively exposed position and could at times be damaged during handling, storage, or transportation.